The present invention relates to a bearing, and more particularly to a hydraulically damped elastomer-metal bearing.
Hydraulically damped elastomer-metal bearings, especially those used for engine or drive assembly suspension purposes in motor vehicle construction, are known in many variations.
Typically, such hydraulically damped elastomer-metal bearings consist of a first load coupling element for the load to be supported, a second load coupling element opposite to the first for fixing the bearing for example to a chassis and a truncated conically-shaped support spring, which is positioned inside a hollow working chamber filled with a damping liquid, which working chamber is separated by a disc-type separating element arranged transversely to the vector of the load to be supported.
When such a hydraulically damped elastomer-metal bearing according to the state of the art is compressed, the damping liquid is pressed out of the working chamber through a throttling channel formed in the disc-type separating element into a receiving or compensation chamber at the other side of the disc-type throttling or separating element. The kinetic energy dissipated in the throttling channels corresponds to the damping factor of the bearing.
These bearings comprise a certain overpressure in the working chamber, when the bearing is compressed and a certain under-pressure when the bearing is unloaded. This means that, when the bearing is unloaded, the damping liquid is sucked from the compensation chamber back to the working chamber.
Especially when having larger amplitudes or certain critical frequencies, the acoustic damping facilities as well as the vibration damping facilities of such hydraulically damped bearings are deteriorated by cavitation effects occurring inside the throttling channels formed in the disc-type separating element. During these working conditions, the bearing shows a disturbing noise and spring and damping characteristics, which are adulterated by foaming effects connected originally to the cavitation effects.